Motor vehicles have a multitude of electronic components/control devices. For example, several control devices are networked via a communications network/via one or several communication channels in modern motor vehicles, wherein the communications network is often a bus line/a bus system, wherein this motor vehicle bus system is usually a CAN bus, a FlexRay bus, or an Ethernet bus. Such a bus system is described, e.g., in Patent Specification DE 102 96 400 B4. The vehicle manufacturer often requires safety-relevant electronic control devices in vehicles to stop communication with the vehicle bus network in the event of an internal fault (also referred to as fail-silent function). The detection of such faults and the interruption of communication is usually performed by means of a software running on a microcontroller of the control device, wherein the software may be executed on the microcontroller to be monitored itself or on a second microcontroller, wherein the second microcontroller serves to monitor a first microcontroller and to interrupt network communication in the event of a fault. Monitoring by means of a watchdog circuit is also well known.
DE 102 55 430 A1 shows, e.g., a circuit arrangement for a control device of a passenger protection system with a microprocessor and a watchdog circuit, wherein the control device serves, e.g., to actuate airbags or seat belt tensioners. The watchdog circuit serves to monitor the operatability of the microprocessor.
A disadvantage of known circuit arrangements for implementing a fail-silent function of a control device consists in the fact that additional hardware (e.g., an additional watchdog circuit or a second microcontroller) has to be installed or that it is necessary to develop special monitoring software. Moreover, the known solutions are not always capable of sufficiently ensuring an interruption of network communication. If, e.g., the microcontroller on which the monitoring software is executed fails itself, an interruption (stop) of network communication by means of software will not be possible any more.